1. Field of the Invention
The present invention relates to methods and apparatus for reducing fluid pressure and regulating fluid flow within a production pipeline or other flowbore while minimizing erosion effects caused by particulate matter within the fluid.
2. Description of the Related Art
Production pipelines are used to transmit hydrocarbons, in the form of crude oil or natural gas, from a producing well to a storage facility or distribution point. These pipelines typically include one or more flow control devices, commonly referred to as “chokes.” The purpose of these devices is to reduce fluid pressure and regulate flow in the hydrocarbon stream. If fluid pressure is not reduced and flow goes unregulated, the high-pressure stream could cause damage to the more vulnerable downstream portions of the pipeline system.
Hydrocarbon streams, particularly natural gas, can often carry solid particulates such as sand. These solid particulates can clog flow in the flow control device and abrade or erode the device's internal components. Accordingly, the flow control device should be resistant to clogging and internal damage caused by such particulate-containing streams.
Various types of flow control devices for pipelines have been proposed to reduce fluid pressure, control fluid flow, and provide resistance to abrasion and/or erosion. These flow control devices primarily utilize some form of stem and seat mechanism, wherein the stem and seat are located within a valve body, and the stem is concentrically located within the seat. During operation, the seat remains static, and the stem moves relative to the seat, exposing a varying area. The exposed area at this single location within these devices controls the amount of pressure drop occurring and the resulting dissipation of energy in the flow stream.
These previously proposed flow control devices suffer from a number of disadvantages. One disadvantage is that the only component within these devices that is utilized to effectuate a significant pressure drop is the geometry of the single varying area. As a result, the pressure drop occurring within the device is primarily limited to that which occurs at this single location within the device. Another disadvantage is that the internal components of the flow control devices are subject to abrasion and erosion as a result of a geometry that brings the components into direct contact with the high pressure, solid particulate-containing hydrocarbon fluid stream.
Prior to the development of the present invention, there has been no choke valve apparatus or fluid flow enhancer apparatus for use as a part of a choke valve which: utilizes controlled geometric principles to effectuate multiple pressure drops at different locations within a flow control device; and encourages erosive solid particulates in a fluid stream to impact surfaces within the flow control device with a degree of angular control that minimizes erosive damage. Additionally, there has been no method of dissipating the energy of, or effectuating multiple pressure drops for, a fluid within a choke valve which: utilizes controlled geometric principles to effectuate such multiple pressure drops at different locations within a flow control device; and encourages erosive solid particulates in a fluid stream to impact surfaces within the flow control device with a degree of angular control that minimizes erosive damage. Therefore, the art has sought methods and apparatus for reducing fluid pressure and regulating fluid flow within a pipeline or other flowbore while minimizing erosion effects caused by particulate matter within the fluid which: utilize controlled geometric principles to effectuate multiple pressure drops at different locations within a flow control device; and encourage erosive solid particulates in a fluid stream to impact surfaces within the flow control device with a degree of angular control that minimizes erosive damage.